Refrigeration



April 19424 w. G. KCJGEL' 2,278,998

REFRIGERATION Filed Dec. 14, 1938 STATE PA if 2,278,998. nemaanarron Application December 14, 1938, Serial No. 245,579

In Germany January'l'l, 1938 i 11 Claims.

This invention relates "to refrigeration, and

more particularly to, improvements for increasing the efiiciency of refrigeration apparatus.

This is accomplished by modifying a refrigeration system by the addition of a separate intermittent system in which one or more parts thereof are in heat exchange relation with the firstmentioned system in such a manner that waste heat from the first-mentioned system is utilized to heat the intermittent system. More specifically, a'first refrigeration system of the absorption type is modified by the addition of an intermittent system so that rectification of vapors produced by the heat in the generator of the first system is improved, and the heat of rectification is utilized to heat the separate intermittent system. By thisarrangement, heat of rectification that would otherwise be lost is recoveredand a greateramount of refrigeration is produced than by a single refrigeration system operating alone, since the intermittent system produces a refrigerating effect when the refrigerat- I ing efiect by the first mentioned system is reduced.

The first or primary refrigeration system may be of the continuous absorption type. When such a system is automatically controlled by a thermostat in response to a temperature condition, the

production of refrigeration by the intermittent system will prolong the intervals when the heat supply to the first system is reduced or shut off. Also,--in accordance with this invention, a fiuid heat transfer circuit for dissipating heat from a heat rejecting part of the first system may be constructed and arranged to eifect cooling of the generator-absorber of the intermittent system when heating thereof by waste heat is stopped. This is advantageous in that quick cooling of the generator-absorber is effected to instigate the production of refrigeration by the intermittent system when the refrigeration produced by the first system is reduced.

contains a solution of refrigerant in absorptionevaporator I2, and an absorber I3. The system liquid, such as ammonia in water, for example, and also an auxiliary agent, or inert'gas," such as hydrogen.

The generator 10 is heated in any suitable manner, as by an electrical heating element I A,

which is fitted in the lower open end of a sleeve I5. By heating generator III, refrigerant vapor is expelled out of solution and. fiows upward through a conduit I6 into condenser II. In condenser II refrigerant vapor is condensed into liquid which fiows therefrom through a conduit The invention will be better understood upon reference to the following description and the accompanying drawing forming a part of this specification, and in which the figure more or less diagrammatically illustrates refrigeration apparatus embodying the invention.

. tion is not limited to the specific refrigeration apparatus shown and hereinafter described. .The system includes va generator it, condenser Ii,

ll into the upper part of evaporator I2. Evaporator I2 may be located in a thermally insulated space I8.

Liquid refrigerant in evaporator l2 evaporates and difiuses into hydrogen which enters through a conduit I9, thereby producing a refrigerating effect. The rich gas mixture of refrigerant vapor and hydrogen formed in evaporator I2 fiows from the lower part thereof through a first passage of a gas heat exchanger 20 and conduit 2| into the lower end of absorber I 3.

In absorber I3 the rich gas mixture fiows counter-current to downwardly flowing weak absorption liquid which enters through a conduit 22. The absorption liquid absorbs refrigerant vapor from the hydrogen and hydrogen weak in refrigerant vapor flows from absorber I3 through a conduit 23, a second passage of gas heat exchanger 20, and conduit I9 into the upper part.

of evaporator I2.

The circulation of gas in the gas circuit just described is due to the difference in specific weight of the columns of rich and weak gas. Since the rich gas is heavier than the weak gas,

force is produced within the system for causing fiow of rich gas toward absorber I3 and fiowof weak gas toward evaporator I2.

Enriched absorption liquid fiows from absorber 83 through a conduit -24 and an inner passage of a liquid heat exchanger 25 to a coil 26 which is disposed about the lower end of sleeve l5. Liquid is raised by vapor-lift action from coil'28 through a tube 21 into the upper part of generator It. Refrigerant vapor expelled out of solution the upper part of absorber I3. This circulation of absorption liquid is effected by raising of liquid by vapor-lift action in generator I 0.

A vent conduit 29 is connected to the lower end ofcondenser II and to the gas circuit, as at one end of gas heat exchanger 29, for example. Conduit 29 extends upwardly from the lower end of 'condenserll and then downwardly to gas heat exchanger 20, whereby any gas which may pass The absorber l3 constitutes a heat rejecting from coil 3| through a conduit 32 to a looped coil 33 which is provided with fins for air-cooling. The vapor is condensed in coil 33 and the condensate' flows therefrom by gravity through a U-shaped trap-34 and conduit 35 back to the coil 3|. The coil 3| constitutes a vaporization portion and the coil 33 constitutes a condenser portion of a closed fluid circuit in which natural circulation 'of fluid takes place. The vaporization of liquid in coil 3| withdraws heat from absorber l3 and the condensation of the vapor in coil 33 gives up heat to the surrounding air. When the heat transfer circuit is operating to cool absorber |3 valve 35, hereinafter to be described, remains closed. When the liquid level in trap'34 rises to the connection of conduit 35 liquid will flo'w through the latter to coil 3|.

The heating element I4 is adapted to be connected to a source of electrical supply by con ductors '3] and 38. A switch 39 is connected to these conductors for connecting and disconnecting the heating element I4 to and from the source of electrical supply. The switch 39 is arranged to be operated automatically by an expansible fluid thermostat. The thermostat includes a thermal element 49 which is located in space l8. The thermal element 49 is connected by a tube 4| to an expansible and contractible diaphragm 42 which is arranged to be adjustably supported in any suitable manner. The diaphragm 42 is connected by a member 43- to operate switch 39. The expan'sible fluid thermostat contains a suitable volatile fluid, as

' is well-known in the art, and operates switch 39 to connect and disconnect electrical heating element l4 to and from the source of electrical supply, whereby space I9 is maintained at a substantially constant temperature or temperature range. 1

In accordance with this invention, in order to recover heat that would otherwise be lost in the primary system just described, a generator-absorber 44 of a separate hermetically sealed intermittent refrigeration system is embedded in insulation and arranged in heat exchange relation with conduit IS. The generator-absorber 44 may contain a solid absorbing agent 45, for example, calcium chloride, strontium chloride, lithium nitrate or the like, suitably treated as known in the art. or any of yarious known solid absorbents, particularly those including an element of the halogen group.

To the generator-absorber 44 is connected 9. vertical conduit 45 which is connected at its upper end to a condenser 41. The condenser is connected by a conduit 49 to an evaporator 43 including a loop connected to a receiver 53. The loop of evaporator 49 is also arranged in the thermally insulated storage space |3.. Any suitable refrigerant may be employed in the intermittent refrigeration system, such as, methylamine, for example.

A coil 5| .is arranged about and in thermal exchange relation with generator-absorber 44. The coil 5| is connected by a conduit 52 to the upper part of looped coil 33, and by a conduit 53 to the lower part of trap 34. In conduit 53 is connected the hermetically sealed valve 33. The valve includes a casing provided with a partition having a port 54 which is adapted to be closed by a valve member 55. The valve member 55 is provided with a stem 56 which is connected by a bellows 51 to the inside of the valve casing. The outer end of stem 56 is pivotally connected to one end of a link 53. The link 58 is pivoted intermediate its ends at 59 and the lower end thereof is pivotally connected to member 43.

- When the expansible fluid thermostat operates to close switch. 39 the valve member 55 is closed; and, conversely, when the expansible fluid thermostat operates to open switch 39. the valve member 55 is opened.

Let us first consider the operation of the intermittent system during operation'of the primary system and when the switch 39 is closed. Under these conditions refrigerant vapor is expelled'from absorption solution in generator I. and condenses in air-cooled condenser Condensate flows from the condenser through conduit l1 into evaporator l2, whereby the liquid evaporates and diffuses into hydrogen to produce v a refrigerating effect to keep space |3 at a desired low temperature.

The generator vapor usually is a mixture of refrigerant vapor and absorption liquid vapor. When ammonia and water are employed as the refrigerant and absorption liquid, for example,

the generator vapor usually is a mixture of ammoniavapor and water vapor. Due to the difference in boiling points of ammonia and water, the water vapor may be removed from ammonia by cooling the mixture to condense out the water.

This is usually termed rectification and the latent heat of condensation resulting from condensationof water vapor is referred to as heat of rectification.

By flowingthe generator vapor in heat exchange relation with generator-absorber 44, heat of rectification is effectively utilized to cause expulsion of methylamine from the absorbent. The methylamine vapor flows through conduit 43 into air-cooled condenser 41 in which it is condensed. The condensate flows from condenser 41 into evaporator 49 and accumulates therein.

During the high pressure vapor expulsion period of the intermittent system, valve 33 is. closed and no heat transfer fluid can flow from trap 34 into coil 5|. The fluid heat transfer circuit therefore operates in the usual manner to withdraw heat of absorption from absorber l3 at coil 3| and give up heat to surrounding air at coil 33.

When space l3 tends to fall below the desired low temperature, the diaphragm 42' of expansible fluid thermostat contracts to open switch 39 and disconnect heating element l4 from the lource from trap 34 into coil Since generator-absorber M is at a relatively high temperature, volatile liquid in coil 5| evaporates and the vapor thus formed flows to coil 33 in which it is condensed. The condensate flows into trap 34 and returns through conduit 53 into coil 5!. The evaporation of volatile liquid in coil 5! withdraws heat from generator-absorber 6d and the condensation of vapors in coil 33 gives up heat to surrounding air. Thus the generatorabsorber is quickly cooled to instigate an absorption period of the intermittent system.

At the beginning of the lower pressure absorption period the evaporator 49 contains the sec-- ondary refrigerant. Since generator-absorber M can readily dissipate heat to.the atmosphere by means, of the closed fluid heat, transfer circuit, refrigerant is absorbed therein, the refrigerant flowing from evaporator 49 through condenser ti and conduit 56 into the generator-absorber. The refrigerant in evaporator is vaporized and withdraws heat from its surroundings thereby producing a refrigerating efiect.

The refrigeration produced by evaporator 69 be employed.

prolongs the interval of time when no heat is supplied to generator It by heating element M. Stated another way, a longer interval of time will elapse before the expansible fluid thermostat will again operate to close switch 89 and start operation of the primary refrigeration system due to rise of temperature in space it. In this manner additional refrigeration is. produced without additional operating cost. v

The intermittent system may be constructed to keep substantially the same desired low temperature in space 18 as the primary evaporator I2 or the intermittent system may be constructed to even lower the temperature in space i8. Evaporator 89 may be constructed as a freezing unit for freezing ice cubes and the like, ifdesired. In

such case the 'expansible fluid thermostat may be arranged to disconnect the heat supplied to generator M at a higher temperature than the-desired low temperature or temperature range at which it is desired to keep space it. When evaporator 49 produces a refrigerating effect the temperature of space It will then be brought down to the desired low value. I

The invention can be carried out in many ways whereby waste heat of a refrigeration system is recovered and utilized to supply heat to an intermittent refrigeration system. The heat of rectification represents waste heat because a part of the heat supply to the generator usually produces absorption liquid vapor which is subsequently condensed out of-the'refrigerant vapor.

The use of heat of rectification is particularly advantageous because the heat is transmitted to the generator-absorber of the intermittent system at a relatively high temperature. Further, by effecting rectification of the vapors in this manner the composition of the refrigerant vapors conde'nsed'in condenser ii and flowing to evaporator i2 is improved and maintained practically constant. Likewise, when a solid absorbing agent, such as calcium chloride, is employed in the intermittent system; the composition of the vapors flowing to condenser ti also remains substantially constant. 7

evaporator and a generator-absorber, control ated with Said mittent system a liquid absorbent agent may'alsc agents, for example, are aqueous ammonia. solution, an aqueous or ammoniacal solution of lithiumnitrate, ammonium thiocyanate, ammonium nitrate or the like.

Although a single embodiment of the invention has been shown and described, it will be apparent to those skilled in the art that varidus modifications and changes may be made without departing from the spirit and scope of the invenation system including a generator arranged in' heat transfer relation with said rectifier so as to be operated by heat input from the rectification of the distillation vapor. 2. The combination with a primary refrigeration system of the absorption type in which refrigerant fluid is distilled from solution in a liquid solvent and including a rectifier,of a secondary refrigeration system including a generator arranged in heat transfer relation with said rectifier so as to be operated by heat input from the rectiflcationof the distillation vapor.. 1

3. The combinationwith a refrigeration system having at least two parts from which heat is dissipated, of an intermittent refrigeration system operated by heat input from'oneofsaid parts from which heat is dissipated, a fluid transfer system in which a heat transfer fluid is adapted toflow and'including one portion in heat exnot utilized representing a total loss afiecting the efllciency of the system. of a second refrigerating system operatively associated with said first system to. provide a compound refrigerating'system.-

and said second system being operatively associflrst system so that said second syslttem is operated by heat dissipated by said pa 5. The combination with a refrigeration system of the absorption type having a cooling ele- -ment, a generator in which refrigerant fluid is distilled from solution in a liquid solvent, and a heater, the aforementioned system dissipating heat due to rectification of distillation vapor, of

anintermittent refrigeration system operated by heat input from the rectification of the distillation vapor, said intermittent system including an means to control said heater, cooling means to facilitate cooling of said generator-absorber, and

- means operatively associated with said control means to render said cooling means inoperative when said intermittent refrigeration system is being heated by heat input from the rectification of the distillation vapor.

6. The combination set forth in claim 5 in which said control meansoperates responsive to a temperature condition afiected by said cooling element and said evaporator.

combination wi a first refrigeration In place of a solid absorbing agent in the inter- Among such liquid absorbent 4-. I I system of "the absorption type having a heat dissipating part, a cooling element, a generator in which refrigerant fluid is distilled from solution in a liquid solvent, a rectifier and a heater, of an intermittent refrigeration system operated by heat input from said rectifler, said intermittent system including an evaporator and a generatorabsorber, control means to control said heater, cooling means including a fluid heat transfer circuit having one part in heat exchange relation with said generator-absorber and another part in heat exchange relation with said heat dissipating part, and means operatively associated with said control means to cause a preponderance of heat transfer-fluid to flow through said other part when said intermittent refrigeration system is beeluding a condenser, an absorption liquid circuit ing heated by heat input from said rectifier, and

to cause a preponderance of heat transfer fluid to flow in said one part when the heating effected by said heaterisreduced.

8. The combination set forth in a closedsystem containing a volatile fluid and having a condensation portion and vaporization portions, said one part and said other part constituting said vaporization portions. 1

9. A method of refrigeration which includes heating a solution of refrigerant and absorption fluids to expel vaporous refrigerant fluid from the solution, removing heat from the expelled va claim 7 in. which said fluid heat transfer circuit comprises having a generator, and a rectifier forming a portionof a conduit for vapors from said generator to said condenser, and a second refrigeration system including an evaporator, a generator, and a conduit connecting said evaporator and the lastmentioned generator, said second refrigeration system being separate from said flrst refrigeration system, and said generator in said second refrigeration system being in heat exchange relation with said rectifler in said flrst refrigeration system.

11. That improvement in refrigeration which consists in utilizing rectification of vapor in one system capable of producing a refrigerating effect to expel a refrigerant from an absorbent in 'a second system in itself capable of producing arefrigerating effect. a

' W1LHELM GEORG zoom... 

